The present invention relates to couplers for joining the ends of successive lengths of pipe or conduit, and in particular to couplers for joining the ends of successive pipes in an exhaust system for vehicles.
It is well known that, in vehicle exhaust systems, particularly those for heavy duty vehicles, such as large trucks, the motors produce a significant amount of vibration in the exhaust pipes. Operation of the motors at continuous speeds for prolonged periods of time can, especially, produce what are known as harmonic vibrations which can cause significant deflections in extended lengths of exhaust pipe. Repeated deflections of the exhaust pipe will, in turn, cause the pipe to weaken with time and ultimately fail. Further, such harmonic vibrations will also be transmitted through the exhaust pipes to the mountings of the pipes, promoting the loosening of the mountings, which can result in the sudden displacement of one or more components of the exhaust system, with the potential for both personal injury and equipment damage.
In addition to the vibrations created by the motor of the vehicle, an exhaust system is also subjected to various tension, compression and bending forces which arise during the operation of the vehicle. While individual components might be made stronger and more massive to resist failure by fatigue, such construction would be undesirable due to weight considerations. Further, by making individual elements stiffer, the vibrations are merely transmitted to the exhaust system mountings or other components, not reduced or eliminated. Accordingly, it is desirable to isolate the exhaust system, or at least components of the system from such vibrations and forces.
It is known that if the pipes of an exhaust system are divided and separated by non-rigid connections, rather than as continuous extended lengths, the development of harmonic vibrations from the motor is precluded or reduced. Such non-rigid connections can be advantageously employed to absorb other tension, compression and bending forces, in addition to motor vibrations.
It is therefore desirable to provide a coupler for joining successive lengths of exhaust pipe, which coupler joins the pipes in a non-rigid fashion and is capable of absorbing tension, compression and bending forces, without transmitting them from one pipe to the next.
An example of a prior art coupler is U.S. Pat. No. 4,792,161 to Usui. In Usui, a pair of concentrically arranged spring coils are utilized to provide a mechanical connection between the pipes to be joined. One drawback of the coupler in Usui is that when the coils are in a stretched or bent position, gaps may form between individual bights of the coil, into which dirt, debris and moisture may invade, which may interfere with the operation of the coils, and lead to ultimate degradation of the coils through abrasion, rusting, and so forth. In addition, the coils (which ar arranged one threaded within the other) are unprotected and exposed to the elements at all times, and are thus susceptible to damage from abrasion and other harmful physical contact. A further drawback of the coupler in Usui is that a sealing ring, positioned between overlapping pipe ends, is relied upon to provide sealing means to prevent escape of the exhaust gases. The sealing ring is subjected to cyclical flexure, tension and compression forces which will ultimately compromise the seal and require replacement of the coupler.
It is therefore an object of this invention to provide a flexible coupler for placement between successive lengths of exhaust pipe for damping and blocking the transmission of vibration and other forces from one length of pipe to the next which is durable and not subject to attack by dirt, debris and the elements.
Yet another object of the invention is to provide a flexible coupler which does not utilize a sealing means positioned between moving exhaust system components which may cause the seal to prematurely yield requiring replacement of the coupler.
It is further an object of this invention to provide a flexible coupler for exhaust pipes which provides means for mechanically connecting the ends of the pipes to be joined, which means are themselves protected from interference and/or degradation by external forces and elements.
Still yet another object of the invention is to provide a flexible coupler apparatus for exhaust pipe systems which provides improved audio isolation to reduce or preclude migration of motor noise into the passenger compartment of the vehicle.
These and other objects of the invention will become apparent in light of the present specification, claims and drawings.